Title says it all.
460
Dual tanks
Electric in tank fuel pumps.
Fuel gauge works on both tanks
Runs good on both tanks until uphill. Even a small incline up for a quarter mile.
Thank you for any help.

 

Ed, we need a little more than that.
You hit a hill and it shuts off or starts to miss fire or just no *****?
How many miles on motor, truck fully loaded or empty?
Last time it was tuned up and all filters changed?
Dave - - - -

 

Sounds like a clogged fuel filter.

 

Sitting at neighbor's property for about a year until last month when I did a labor trade for it. He had picked it up from a local family, drove it home and thought the carb needed rebuild. Delivered carb to local shop and they told him it was not good enough for rebuild. It sat for 8 months.

I ordered remanufactured factory Holley from Summit Racing and installed.
Added water stabilizer to both fuel tanks and let sit for a couple days.
Added Lucas gas treatement and 10 gallons of fuel to both fuel tanks and let sit for a couple more days.
Pumped out about a half gallon of fuel from fuel line just before the carb to clean the line.
Added clear plastic Wix fuel filter to the fuel line just before the carb.
Hooked up fuel line and truck fired up within half dozen cranks.
Back truck to his house and tore off his roof, loading it in the truck.
Drove home and to dump next day.
Ran rough but made it to dump, around town and back up the mountain to home
Installed new plugs, cap, rotor, air filter. Wires tested good.
Oil change with Lucas oil treatment and wix filter.
Followed up with another oil and filter change after 100 miles.
In this time, about a week, truck ran great except at idle was mildly rough.
Was spending time working on vacuum lines as the cause and required smog.
Old smog man said the numbers from his machine showed major vacuum leak and check the throttle body with carb clean. Said its common for throttle body seal to fail with age and it's not replaced with rebuild.
Truck increased rpm's when spraying carb clean at throttle body.
Ordered return coupon from Summit and am considering options.
Have been advised that a new Holley 600cfm carb will pass smog inspection.
Still driving truck during this time, up and down the mountain with both fuel tanks.
One day, while driving it uphill at 35mph, it surged like hitting a body of water.
Applied clutch and feathered gas pedal.
Engine picked up, released clutch and drove 100 feet. Another surge and repeated the clutch and gas pedal method.
Did this for 5 mile up the mountain until home.
Truck drove great around the property. No problems.
Inspected engine and noticed "some" white sediment in wix fuel filter. Not enough to stop flow.
Drove truck down mountain to pick up lumber rack. 20 miles.
Slight incline while changing roads and surged and stopped running.
Coasted backwards onto flat area and started after a dozen cranks of engine.
Drove around town, picked up lumber rack and headed back up mountain.
3 miles up it started losing fuel again and clutch pedal method didn't catch it.
Stopped running and being that it was on an uphill, it did not start.
Unable to back it down our 2 lane mountain road safely, had it towed home.
Started up after a dozen cranks.
Compression check showed all 8 cylinders at 110-112 pounds approximately.

Willing to add pictures with some directions on how.

 

Don't know what that white stuff is in the filter but it cant be good.
Does the truck have electric fuel pump(s) in tanks or 1 on the side of the motor? I see from your other posts you have electric pumps, 1 in each tank.
I take it this happens on either tank?

Just thinking the next time it dies pull off the air filter open the choke if closed and looking down inside the carb move the throttle and look for fuel squirting into the carb.
If nothing then I would change ALL the rubber fuel line parts. They may look good on the old side but they fall apart on the inside and could be plugging the fuel from getting to the carb.

If that all fails it might be time to drop the tanks to see what the insides look like and if the pickup filter socks are still in place and in good shape.
I have seen the socks fall apart and plug the pickup tube.
Dave ----

 

Electric in tank fuel pumps. (Updated thread)

White sediment is unknown.

Runs great at level ground.

Fuel lines look like plastic along frame to/from tanks.
One fuel line going to rear tank is blue.

Looks like will have to drop side/front tank to detach lines from selector valve.

Not hearing pumps come on with key movement to on position. Maybe both pumps went bad and fuel is being siphoned from engine compression. Enough to keep it going on level ground and not enough for uphill fuel consumption.

Posted thread about testing fuel pumps at selector valve with 12 volt battery.
Any knowledge on which pin in the 5 pin connector at selector valve to activate with the battery for front and rear tank pumps?

Thanks

 

I did see that post and sorry to say I don't know the pin out.
Thing is "I" don't think and could be wrong, that power goes thru the valve then to pumps.
I want to say from what I seen posted the switch sends power to the relay then to the pumps but..........I COULD BE WRONG???


There is some information posted in here on the fuel system for 460 motors.
There is some more information here ???Gary's Garagemahal - Bullnose Forum
Click on the 3 little lines in the upper left corner for a drop down for different info.
Look for fuel and maybe electrical.
Dave ----

 

They are powered through the selector valve.
Wiring diagram on line is too blurred for me to see the color of specific wires.
Probably my eyes are too blurred to read it!-)

Also, not sure if the pumps operate on 12 volts.
Can I test the pumps by hooking a 12 volt battery to the specific wire lead at the selector valve connection?
Which color wire is the hot for front/rear tank?

Thanks.

 

If that system is original, the selector valve on the side of the frame has nothing do to with pump power. It does have the sending unit wires running through it.

You will not hear the pumps run when you first turn the key to run. They only run when the engine is cranking, or you have oil pressure and the fuel pump relay is activated.

When it runs 100 feet and then quits. Runs another 100 feet and then quits. That sounds like fuel starvation. You are cranking the engine, and as you are doing this the fuel pumps are getting power from the "I" terminal of the starter solenoid. They are filling up the bowls in the carb. It finally starts, the truck is idling and not using much fuel. As you take off and start using more fuel, it is running on the fuel stored in the fuel bowls, and the fuel is not being replaced fast enough. So it runs for a little bit and when all the fuel is out of the bowls, it stops again till you crank and fill it up again.

The fuel system on the 460 trucks is fairly complex. Bunch of wiring, oil pressure switch, relays and a fuel return system with a return orifice. The return orifice piece can get clogged with junk from the tanks. This is the gizmo in the fuel line right before it enters the carb.

 

I have a hard time thinking it is electrical.
Guess it could be a bad relay? Heats up when working and then stops working then cools off and starts again but why only going up hill so that is also hard to take.


I have seen a post of the connection on the oil psi switch caused issues with pumps failing at times. The oil psi stops the fuel pumps from running if the motor is not running.


If it is electrical, with motor running try the wiggle test on the wiring to see if it stops the pumps. Thing is being you have a carb the pumps would have to stop running for a long time for the carb to run dry.


Sorry I cant help more. I never followed too close the 460 fuel issues as I don't have one and don't plan on getting one.
Dave ----

 

It does seem to be the original system and it is understood the selector valve only has the wires running through it. Thanks

Oh, right. The oil pressure switch and fuel pump relay connection is why it doesn't pump with key movement to on. Thanks.

On the 100 foot 5mile journey up the mountain: the truck loses fuel pressure and I kept it going by clutching the tranny and feathering the gas pedal. (I didn't crank the starter)
So, since it still had oil pressure, it still pumped fuel into the system and got enough to go another 100 feet and so on.

Any guidance where to buy a new return line connector? (The orificre piece that may be clogged)

***The question still remains as to why this only happens uphill/small incline.***

 

If that happens I would think the carb would get too much fuel psi and flood the carb no?
Dave ----

 

Uphill/small inclines use more fuel. Idling or cruising on level ground, you are not using as much fuel. To test this theory get a load on it, and if you have a nice empty stretch of straight highway, push the pedal on down and see how long it runs and if it starts coughing. You may get too fast before it uses all the fuel, but it would be a interesting experiment.

 

The main passage to the carb inside the orifice piece gets clogged. I want say there is a screen in there. A guy I work with had one of these trucks, and the plastic pickup piece in the fuel tank disintegrated and those little black pieces of plastic went up and clogged the orifice piece and would not let fuel pass through to the carb. I think he took this piece off and was able to flush it out is why he knew what had happened.

 

Ok. Will try flushing that piece out.
No parts store locally has or knows anything about this piece.
Is there a replacement out there?
Also, unable to read the part number on it.
Anyone know the part number?

The day I did the tune up, about a week before the problem came up, the truck ran great uphill. No problems.
The next day I did the oil/filter change with the oil treatment and drove aggressively as the directions on the treatment product stated. Aggressively, meaning, I was driving it in all gears very fast, then slow, then fast. Downshifting and flooring it, then cruising. All in the mountains where I live, mostly uphill on the way out and downhill on the way back.

It ran beautifully!